Research On Key Techniques Of In-situ Sharing For Geographical Model In Distributed Network Environment

Sharing of geographical models in network environment is an important problem which must be solved in geographic information technology following geographical data sharing and has been emphasized highly in academia. At present, there is no other complete solution for sharing of geographical models than to using centralized way and sticking in a specific study area. The centralized pattern of sharing geographical model might face several disadvantages, like incapable for coordination of geographical models from diverse research areas, low-severity, high runtime overhead, incompatibility and high cost of recoding as well as code migration which could not make geographical model running effectively. With the computer technology and Internet technology growing mature gradually, personal computer has gained a capability to serve for multiple-access and provide basic computation which only could be done by the Server many years before. Therefore, it is totally possible to deploy geographical model locally and make it operating locally in the same way. This novel idea will make system load distributed to all the computers in the network space which is the so called distributed in-situ sharing of multi-source heterogeneous geographical models.Based on the application features and sharing demand of geographical models, this thesis has analyzed a novel way which is the so called in-situ sharing and summarized the key problems of sharing of geographical models in heterogeneous network environment from two aspects of model provider and user. Moreover, a basic thought has been analyzed based on current development of techniques. The main content and result of this paper include:(1) The intrinsic features of geographical model have been analyzed and summarized. At the same time, some characteristics of geographical model existing in the process of application and related sharing demand have been refined. Furthermore, from two aspects of model provider and user, key problems in heterogeneous network environment needed to be worked out have been summarized.(2) The distribution characteristic of geographical model has been studied and the technique of labeling and locating of geographical model resource has been introduced based on DHT (Distributed Hash Table) algorithm which could give a support to efficient searching of geographical model.(3) According to problems caused by heterogeneous network when doing sharing of geographical model, the technique of invoking geographical model with network traversing has been introduced based on NAT-T (Network Address Translation-Traversal) which is aiming to make geographical model accessing lucidly through heterogeneous network environment.(4) The extension of WSDL (Web Services Description Language) from web services has been made to be GSDL(Geo-model Service Description Language) and the improvement to SOAP (Simple Object Access Protocol) has been made to be GSMP (Geo-Model Service Message Protocol) which are all to be designed to meet the needs of in-situ sharing of geographical model.Based on sharing requirement of geographical models in distributed network, being established in current development of techniques and orienting to common features of in-situ sharing of geographical model, this research is aiming to solve probles in resource labeling and locating and heterogeneous network environment as well as giving a support to the in-situ sharing of multi-source heterogeneous geographical model in distributed network environment with the help of key techniques mentioned in this research which has a relatively high application value.